Our preliminary data suggests that during early C. elegans embryogenesis (around the 4E stage) pharyngeal precursors lose their pluripotency and commit to become a pharynx. Despite of a wealth of data gathered on the roles of transcriptional factors and nuclear re-organization in development, we still do not understand the mechanism of the transition from pluripotency to the cell type commitment. The ultimate goal of my proposal is to use the C.elegans pharynx as a simple model system to study how cell fate specification is regulated. I will address this questions by comparing genotypic landmarks of pluripotent vs. committed pharyngeal cells using genome-wide microarray analysis; by studying how changes in expression levels of different regulatory factors affect a period of cell pluripotency using RNA interference assay; and finally, by examining nuclear organization of pharyngeal genes in pluripotent vs. committed cells using Fluorescent In-Situ Hybridization analysis. Identification of genes involved in cell fate specification and determination of the relationship between nuclear organization of pharyngeal genes and cell competency to reprogram their cell fate will lead us to greater understanding of the mechanisms of cell fate specification during early embryogenesis.